The present invention relates to a method and a device for contact-free energy and signal transmission on textile machines, especially twisting machines. Energy transmission takes place between a first stationary part and a second stationary part separated by an air gap, wherein at least one component consisting of an electrically non-conducting material is moved through the air gap, wherein an alternating current signal of a frequency of at least 10 kHz is inductively transmitted by a transformer, having a primary side arranged at the first stationary part and a secondary side arranged at the second stationary part, wherein the primary side and the secondary side are separated by the air gap,
A method and a device with the aforementioned features is known and disclosed for a twisting machine in DE-C-1 510 854. In the known device the energy transmission is performed between the stationarily arranged primary side and the stationarily arranged secondary side of a transformer whereby between the two transformer halves the yarn balloon extends. More details of the embodiment of the transformer are not disclosed in this document. The disclosed embodiments show that the transformer is suitable only for transmission of small power output. This is already indicated by use of an iron core at transmission frequencies of more than 1,000 Hz. For higher power output, i.e., power output above 50 W, the power loss due to the high remagnetization losses could not be dissipated without additional cooling measures. A further disadvantage of the known device is that due to the analog control of the disclosed functional components (change of the primary voltage of the transformer) a plurality of transformer units are required as soon as multiple functional components (for example, brake and motor) are to be controlled. A further principal disadvantage of such an analog control method is that a highly precise control, for example, precise rpm control of motors, cannot be realized because especially for large air gaps the tolerances of the coil windings and the air gap adjustment cannot be maintained with sufficient precision at acceptable expenditure, and data transmission, for example, by a preset nominal value is not possible.
A contact-free transmission of signals and electrical energy is also disclosed in EP-0 525 495 A1. In this known arrangement an axial transformer arrangement with a primary coil and a secondary coil as well as core of ferromagnetic material is used in which, for additional contact-free transmission of changing signals, in direct vicinity of the primary coil and of the secondary coil at least one sender and at least one receiver are arranged which can be alternatingly connected to the electric receiver and the electronic sender device, which are embodied as large-surface antennas and are combined to a common constructive unit with the primary coil, the secondary coil, and/or the core of the transformer.
The primary coil and the secondary coil of the transformer can be arranged so as to be rotatable relative to one another. By employing two such known transformers acting as axial transformers it would be possible, in principle, to transmit in a textile machine energy and signals from a first stationary component through a rotating component to a second stationary component. However, for the high rpm (greater than 10,000 rpm) occurring in textile machines such an arrangement cannot be provided with sufficient operational safety. Tests with such arrangements show again and again the technical limits resulting from insufficient centrifugal force stability of the brittle ferrite material that has the tendency to form cracks. This is also true when the transformer is embodied as a radial transmitter.
Furthermore, in these known arrangements the signal transmission is carried out parallel to the energy transmission on separate paths via additional coils or by coupling elements embodied as inductive or capacitive antennas. If additional windings are used, this results in undesirable large space requirements. When employing antennas, the power and data transmission is conventionally performed by employing different carrier frequencies, i.e., the energy transmission is carried out conventionally in the kHz range while the signal transmission is performed in the MHz range. The expenditures for the required components results in high costs which, especially for textile machines having multiple work stations, cannot be justified.
Document DE 41 25 145 A1 relates to a device for contact-free transmission of electrical energy and changing signals with an axial transformer arrangement with primary and secondary coils and a core made of ferromagnetic material. In direct vicinity of the primary coil and the secondary coil at least one sender and one receiver are arranged which are embodied as large-surface area antennas whereby the primary coil and secondary coil together with the corresponding antennas can be displaced relative to one another or rotated relative to one another. With respect to the use of such devices for energy and signal transmissions the remarks made in regard to the aforementioned document apply here as well.
From DE 195 45 220 A1 an arrangement for contact-free transmission of signals between vehicle components that can be moved linearly relative to one another is known. It is especially suitable for transmission of energy and control signals between the car body of a vehicle and the driver or front passenger seat. The arrangement includes a transmission device having primary and secondary coils in separate half-shell cores which are embodied as rails that can glide along one another and have such a contour that they form a closed circuit for magnetic flow between the primary and the secondary coil. With this arrangement energy and signal transmission at a textile machine through a rotating component is not possible.
It is therefore an object of the invention to improve a method of the aforementioned kind such that across an air gap through which at least one component, for example, a yarn balloon is moved, electrical energy and signals can be transmitted from the first stationary component, for example, the machine frame of a twisting machine, to a second stationary component, for example, a twisting spindle, such that the following conditions are fulfilled:
1) Any number of functional components of the second stationary component can be controlled which second stationary component is surrounded by the movable component; PA1 2) The moved component can rotate at high rpm (for example, more than 10,000 rpm); PA1 3) An energy transmission with power output greater than 50 W across a relatively large air gap (greater than 1 mm) is possible; PA1 4) It is possible to perform data transmission preferably unidirectional, but alternatively also bidirectional, without additional inductive or capacitive coupling elements embodied as antennas.